Horn adjustment apparatus and method



April 2, 1957 J; MOSIER HORN ADJUSTMENT APPARATUS AND METHOD Filed Feb. 4, 1955 IN VEN TOR JACQUES MOS/ER arr) United States PatentO 2,787,763 HORN ADJUSTMENT APPARATUS AND METHOD Jacques Mosier, Ypsilanti, Mich., assignor to Ford Motor Company, Dearborn, Mich., a corporation of Delaware Application February 4, 1955, Serial No. 486,235

2 Claims. (Cl. 324-158) This invention deals with electrical apparatus and more particularly with a method and apparatus for adjusting automobile horns during the process of manufacture.

In the conventional automotive horn a vibratory motor is employed to oscillate a metallic diaphragm which in turn generates the sound waves which constitute the audible warning signal. These horn motors employ a typical door bell type circuit in which the initial movement of an armature of a solenoid breaks the solenoid circuit which in turn permits the return of the solenoid armature and re-establishes the solenoid current. This gives rise to a continuous oscillatory movement, the frequency of which is determined by the physical and electrical constants of the apparatus.

In the large scale production of such horn motors it has been found necessary to adjust individually each motor to insure the proper setting of the contact points which control the solenoid. Since the horn must be completely assembled as to the auditory parts this testing procedure is inherently an extremely noisy undertaking. This invention has been specifically developed to enable this adjustment to be made accurately and quickly without causing actual operation of the horn.

This invention may be best understood by reference to the drawings in which:

Figure l is a plan view of a horn motor and Figure 2 is a sectional view of the horn motor taken along the line 2--2 of Figure 1 and Figure 3 is a diagram of the electrical circuit employed for checking the horn.

Turning first to Figure 2, the diaphragm is shown closing the lower portion of cup 11. It is the oscillations of this diaphragm 10 which produce the actual sound. Diaphragm 10 is weighted by slug 12 which lowers the natural frequency of oscillation of the system and forms an integral part of the magnetic circuit. This magnetic circuit comprises slug 12, cup 11, washer 13 and post 14.

Post 14 is surrounded by coil 15 which energizes the magnetic circuit. Coil 15 is in turn controlled by a buzzer or door bell type circuit which includes contact points 16. The upper of contact points 16 is securely riveted to spring 17 and the lower of contact points 16 is fastened to rigid member 18. Rigid member 18 is electrically isolated from the remainder of the structure by insulators 19 and 20. Insulator 20 is similar in shape and coextensive with spring 17 and is centrally cut away to accommodate contact upper point 16. The electrical energy enters the unit through a connection made to the left end of rigid member 18, flows the length of rigid member 18 to the lower one of contact points 16, hence to the upper one of contact points 16 along the length of spring 17 and hence through conductor 21 into coil 15. The circuit is completed through conductor 22 (Figure 1) which is solidly grounded on cup 11.

Pin 23 is received axially in post 14 and supported at its lower end by the central portion of slug 12. The upper end of pin 23 contacts the outboard section of insulator 20. When electrical energy is applied to rigid clcg member 18 and hence to coil 15, slug 12 and diaphragm 10 are attracted towards post 14. This movement of slug 12 in turn moves pin 23 axially and upwardly against insulator 20 which in turn flexes spring 17 upwards and opens contact points 16. The opening of contact points 16 interrupts the flow of current, causes a collapse of the magnetic field and a subsequent return of slug 12 and diaphragm 10 to the normal position. This cycle is repeated in the neighborhood of 400 times per second to produce the desired note. Resistor 24 (Figure 1) is shunted across contact points 16 to prevent excessive arcing due to the high voltage generated by the sudden collapse of the magnetic field.

As is more clearly shown in Figure 1, rigid member 18 is provided with two openings. Opening 25 is threaded to receive the screw which secures the necessary electrical connection. Opening 26 is provided just outside of the portion or rigid member 18 which is held in place by insulators 19 and 20. Opening 27 is provided in tab 28 of washer 13 to enable the rapid and accurate adjustment of the spacing of the contact points 16 during assembly operation. From a study of Figure 1, it will be seen that tab 28 has been provided on washer 13 and that this tab 28 extends beyond spring 17, rigid member 18 and insulators 19 and 20 and forms extensions 29. After the motor has been finally assembled, the contact point spacing is readily and accurately adjusted by applying a special wrench to that portion of tab 28 which extends beyond rigid member 18, insulators 19 and 2t) and spring 17 and bending tab 28 to rotate the entire contact assembly about an axis passing through opening 27 in tab 28. This opening 27 has been specifically provided to localize all bending at this particular locale during the adjusting operation. Opening 26 has similarly been provided so that should excessive force be accidently applied to rigid member 18, this member will bend across opening 26 which is advisedly made weaker than the metal of tab 28 adjacent opening 27 so that the adjustment of the contact points cannot so be disturbed.

The adjustment of the horn motor as described above is facilitated by use of the apparatus shown in Figure 3. This drawing depicts coil 15, contact points 16, and resistor 24 illustrated in Figures 1 and 2. To test a horn a direct potential of about one or one-half volts is applied across coil 15 by conductors 30 and 31. It will be noted that this current is not subject to interruption by contact points 16. Transformer 32 is arranged with its secondary in series with coil 15. Primary 33 of transformer 32 is energized from any conventional 60 cycle commercial source. The windings of transformer 32 are chosen so as to apply an alternating bias of about A of a volt to coil 15. It will be noted that conductor 31 is solidly grounded at 34. Conductor 35 is connected to that contact point which is electrically remote from coil 15. Conductor 35 is grounded as at 36 through primary 37 of transformer 38. The secondary 39 of transformer 38 energizes neon lamp 40. Incandescent lamp 41 is connected to conductor 35 between contact point 16 and primary 37 of transeformer 38.

The operation of this testing procedure is as follows: The application of a direct potential of 1 /2 volts to a horn solenoid designed to operate at 6 volts will cause slug 12 to move only a portion of the way towards cup 11 and this movement is ordinarily of the same order as that required to open contact points 16 in service. The alternating current bias applied by transformer 32 serves to further impress a physical vibration upon slug 12 which vibrations have as their center the point of rest of slug 12 if no alternating current bias is applied. This alternating current bias on a properly adjusted horn is sufiicient to cause contact points 16 to open and close in synchrony with the applied alternating current. This rapid opening and closing of contact points 16 interrupts the flow of current from conductor 30 through contact points 16, conductor 35 and primary 37 to ground 36. This interrupted current causes the generation or su'fiic ient potential in secondary 39 of transformer 33 to cause glow lamp 40 to operate.

Thus in making an adjustment the operator need only set contact points 16 so that the glow lamp 40 is operating and he is then assured that contact points 16 are spaced so that the horn will operate properly when the correct voltage is applied. Lamp 41 in conjunction with 2 ohm resistor 24 serves to further indicate the actual position of contact points 16.

It will be understood that the invention is not to be limited to the exact construction shown and described, but that various changes and "modifications may be made without departing from the spirit and scope of the invention, as defined in the appended claims.

What is claimed is:

l. The process of testing and adjusting vibratory horn motors comprising impressing upon the operating coil of said motor at a point between said operating coil and the motor contact points a direct potential having superimposed thereon an alternating potential, said direct potential being suificient to open the motor contaet'points but less than that for which the motor is designed to normally operate, said alternating potential being sufficient to cause the contact points to open and close in synchrony with the alternating potential 'as said alternating potential alternately reinforces and opposes the direct potential and causing a portion of. the current resulting from the application of the direct and alternating potential to flow through the motor contact points and through a device responsive to the pulsating current generated by the opening and closing of the contact points.

2. The process of testing and adjusting vibratory horn motors comprising impressing upon the operating coil of said motor at a point between said operating coil and the motor contact points a direct Lpotential having superimposed thereon an alternating potential, said direct 'potential being sufiicient to open the motorcontact points but less than that for which the moor is designed to normally operate, said alternating potential being sulficient to cause the contact points to open and close in synchrony with the alternating potential as said alternating potential alternating reinforces and opposes the direct potential and causing a portion of the current resulting from the application of the direct and alternating potential'to flow through the motor contact points and through a transformer responsive to the pulsating current generated by the opening and closing of the contact points, said transformer energizing an indicating device.

References Cited in the file of this patent UNITED STATES PATENTS 

